In an extra-large mixing bowl, toss together the popcorn and nuts. Set aside.
In a medium saucepan over high heat, bring the sugar, 1 1/3 cups water, corn syrup, vinegar and salt to 260 degrees F (the hard-ball stage) on a candy thermometer. Stir in the vanilla. Pour the hot mixture over the popcorn and nuts, tossing gently to coat. When the mixture is cool enough to handle, dip your hands in water to moisten and form the popcorn into 4-inch balls. Place on waxed paper until cool. Wrap in clear plastic wrap and tie with a decorative ribbon.
Cook's Note: Use caution when handling hot syrup. Syrup stays especially hot on nuts.